Semiconductor stacking structure, and method and apparatus for separating nitride semiconductor layer using same

ABSTRACT

A semiconductor stacking structure according to the present invention comprises: a monocrystalline substrate which is disparate from a nitride semiconductor; an inorganic thin film which is formed on a substrate to define a cavity between the inorganic thin film and the substrate, wherein at least a portion of the inorganic thin film is crystallized with a crystal structure that is the same as the substrate; and a nitride semiconductor layer which is grown from a crystallized inorganic thin film above the cavity. The method and apparatus for separating a nitride semiconductor layer according the present invention mechanically separate between the substrate and the nitride semiconductor layer. The mechanical separation can be performed by a method of separation of applying a vertical force to the substrate and the nitride semiconductor layer, a method of separation of applying a horizontal force, a method of separation of applying a force of a relative circular motion, and a combination thereof.

The present application is a 35 U.S.C. § 371(c) submission internationalapplication no. PCT/KR2015/007271, filed on 13 Jul. 2015 and publishedon 21 Jan. 2016 with publication no. WO 2016/010323 A1, which claimspriority to Korean Patent Application No. 10-2014-0088503 filed in theRepublic of Korea on 14 Jul. 2014, the disclosure of which isincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a semiconductor layer of galliumnitride (GaN) or mixed nitride of gallium and other metal and itsformation method. Furthermore, the present disclosure relates to anelectronic or opto-electronic device including the layer, a nitridesemiconductor substrate and its manufacturing method. The technicalfield of the present disclosure may be, in broad senses, defined as asemiconductor stacking structure for forming a nitride semiconductorlayer with few crystal defects and high quality on a substrate and itsformation method.

BACKGROUND ART

Nitride semiconductor of elements in Group III or V in the periodictable occupies an important position in the field of electronic andopto-electronic devices, and this field will be more important in thefuture. In practice, nitride semiconductor has a wide range ofapplications, ranging from laser diodes (LDs) to transistors that canoperate at high frequency and high temperature. Furthermore, the rangeof applications includes ultraviolet light detectors, elastic surfacewave (SAW) devices and light emitting diodes (LEDs).

For example, gallium nitride is known as a suitable material forapplications of blue LEDs or high temperature transistors, but is beingwidely studied for the use of microwave electronic devices but notlimited thereto. Furthermore, as stated herein, gallium nitride has awide range of applications including gallium nitride-based alloys suchas aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN) andaluminum indium gallium nitride (AlInGaN).

In devices using nitride semiconductor such as gallium nitride, the mostfrequently used substrate for growing a nitride semiconductor layer is a“heterogeneous” substrate such as sapphire, silicon carbide (SiC), andsilicon. However, because these heterogeneous substrate materials have alattice constant mismatch and a difference in thermal expansioncoefficient with nitride, a nitride semiconductor layer grown on theheterogeneous substrate includes many crystal defects such asdislocation. The defect acts as a key factor that degrades theperformance of nitride semiconductor devices such as LEDs.

Because a sapphire substrate has a higher thermal expansion coefficientthan gallium nitride, when gallium nitride is grown at high temperatureand then cooled down, compressive stress is applied to a gallium nitrideepitaxial layer. Because a silicon substrate has a lower thermalexpansion coefficient than gallium nitride, when gallium nitride isgrown at high temperature and then cooled down, tensile stress isapplied to a gallium nitride epitaxial layer. For this reason, asubstrate warpage phenomenon occurs, and to prevent substrate warpage,the substrate thickness increases. The use of a thick substrate onlycontributes to the reduced superficial phenomenon, and is not technologythat reduces the stress of a thin film itself. If the stress of a thinfilm itself is reduced, an advantage is that a thin substrate can beused. Furthermore, to separate a chip from a fabricated LED, a substrateneeds to be ground while leaving about 100 μm, and in this circumstance,if a thin substrate can be used, great benefits will be gained in theaspect of LED production.

In some cases, the nitride semiconductor layer formed on theheterogeneous substrate should be separated from the heterogeneoussubstrate according to the need, and prior art proposed laser lift-off.However, even though a laser lift-off process is used, substrate warpageoccurs due to a difference in thermal expansion coefficient between asapphire substrate and nitride semiconductor, or a nitride semiconductorlayer is melted using a laser and peeled off, so a side effect is theoccurrence of thermal stress during the process due to high temperatureheat at a local area. The laser lift-off process involves thermal andmechanical deformation and decomposition of nitride semiconductor. Dueto laser beam impacts, the nitride semiconductor layer is susceptible todefects such as cracks and the nitride semiconductor layer may bedamaged, and further, the nitride semiconductor layer is prone tobreakage, and thus, the process is unstable.

Therefore, there is the demand for a substrate separation method withhigh reliability or a method for obtaining a high quality nitridesemiconductor substrate or nitride semiconductor device.

DISCLOSURE Technical Problem

The problem to be solved by the present disclosure is to provide asemiconductor stacking structure that forms a high quality nitridesemiconductor layer with reduced stress applied to the nitridesemiconductor layer when growing the nitride semiconductor layer and iseasy to separate the nitride semiconductor layer from a substrate withno need for laser lift-off, and a method and apparatus for separating anitride semiconductor layer using the same.

Technical Solution

To solve the above problem, a semiconductor stacking structure accordingto the present disclosure includes a monocrystalline substrate of aheterogeneous material from nitride semiconductor, an inorganic thinfilm including a leg portion contacting with the substrate to define acavity between the inorganic thin film and the substrate and an uppersurface portion extending from the leg portion parallel to thesubstrate, wherein at least a part of the inorganic thin film iscrystalized with the same crystal structure as the substrate, and anitride semiconductor layer grown from the crystalized inorganic thinfilm on the cavity.

Particularly, the cavity may consist of a plurality of cavitiesseparated from each other, and may be a line type pattern extending inthe direction perpendicular to a direction in which a lateral growthrate of the nitride semiconductor layer is fast. The nitridesemiconductor layer may be in combined or non-combined form. The nitridesemiconductor layer may be continuous or discontinuous in horizontaldirection. The nitride semiconductor layer may consist of at least twofilms. An inorganic thin film defining cavities such as the above may befurther formed between the at least two films.

There is provided a method for separating a nitride semiconductor layeraccording to the present disclosure. After a sacrificial layer patternis formed on a monocrystalline substrate of a heterogeneous materialfrom nitride semiconductor, an inorganic thin film is formed on thesacrificial layer pattern. The sacrificial layer pattern is removed fromthe substrate with the inorganic thin film, to form cavities defined bythe substrate and the inorganic thin film. Subsequently, at least a partof the inorganic thin film is crystalized with the same crystalstructure as the substrate, and a nitride semiconductor layer is grownfrom the crystalized inorganic thin film on the cavities. Subsequently,the nitride semiconductor layer is mechanically separated from thesubstrate.

The growing of a nitride semiconductor layer may include forming thenitride semiconductor layer as a plurality of nitride semiconductorlayers separated from each other.

The sacrificial layer pattern may be formed by various methods. Thesacrificial layer pattern may be formed by photolithography afterapplying a photoresist film onto the substrate, or may be formed bynano-imprint after applying resin for nano-imprint onto the substrate.Alternatively, the sacrificial layer pattern may be formed by adheringorganic nanoparticles onto the substrate.

Preferably, the forming of an inorganic thin film is performed withinthe temperature range in which the sacrificial layer pattern is notdeformed. The cavities are where the sacrificial layer pattern isremoved away. Thus, the cavities conform to the shape and size andtwo-dimensional array of the sacrificial layer pattern. Accordingly, forthe cavities to have the controlled shape and size and two-dimensionalarray, it is required to set the shape and size and two-dimensionalarray of the sacrificial layer pattern.

Another method for separating a nitride semiconductor layer according tothe present disclosure performs mechanical separation of a substrate anda nitride semiconductor layer in the semiconductor stacking structureaccording to the present disclosure.

Still another method for separating a nitride semiconductor layeraccording to the present disclosure performs mechanical separation of asubstrate and a nitride semiconductor layer in other semiconductorstacking structure including an interfacial layer with cavities betweenthe substrate and the nitride semiconductor layer even though thesemiconductor stacking structure does not follow the present disclosure.

When the nitride semiconductor layer is separated from the substrateusing this method, the nitride semiconductor layer may be transferred ormoved to vertical or horizontal LEDs or any type of substrates tomanufacture LEDs or nitride semiconductor free-standing substrates.

In the method for separating a nitride semiconductor layer according tothe present disclosure, the mechanically separating may be performed bya method for separation by applying a force in vertical direction to thesubstrate and the nitride semiconductor layer, a method for separationby applying a force in horizontal direction, a method for separation byapplying a force in relative circular motion, and its combined method.

Particularly, in the case of the method for separation by applying aforce in vertical direction to the substrate and the nitridesemiconductor layer, it is preferable to perform end point detection bysensing the thickness or pressure at which the substrate and the nitridesemiconductor layer are compressed in vertical direction.

The method for separating a nitride semiconductor layer according to thepresent disclosure may further include, after separating the nitridesemiconductor layer from the substrate, transferring the separatednitride semiconductor layer to other substrate or packaging theseparated nitride semiconductor layer.

An apparatus for separating a nitride semiconductor layer according tothe present disclosure performs mechanical separation of the nitridesemiconductor layer from the substrate in the semiconductor stackingstructure according to the present disclosure or other semiconductorstacking structure including an interfacial layer with cavities betweenthe substrate and the nitride semiconductor layer even though thesemiconductor stacking structure does not follow the present disclosure.

The apparatus may include a pair of separation member as jigs appliedrespectively to the substrate and the nitride semiconductor layer of thesemiconductor stacking structure. The separation members and thesemiconductor stacking structure may be temporarily adhered to eachother. The temporary adhesion may be any of an adhesive layer, adhesivecoating, an adhesive tape, an electrostatic force or a force by vacuum.

The apparatus may include a driving unit to apply an external force tothe semiconductor stacking structure, and a control unit to control thedriving unit. The driving unit may apply relative compression, tension,shear, torsion, and its combined external force to the substrate and thenitride semiconductor layer.

The separation apparatus according to the present disclosure may applythe external force while at least one of a pair of separation member istemporarily adhered to the semiconductor stacking structure, the pair ofseparation member as jigs applied respectively to the substrate and thenitride semiconductor layer of the semiconductor stacking structure.While any of the separation members is fixed, the external force invertical direction, horizontal direction or rotation may be applied tothe other separation member against the remaining one.

Particularly, it is preferable to fix any of the separation members anddrive the other in vertical direction against the remaining one toprovide a compressive force, and release the compressive forceimmediately after the nitride semiconductor layer and the substrate areseparated by destruction of the inorganic thin film or the interfaciallayer. In this instance, the control unit may control the driving unitto stop relative movements of the separation members or move theseparation members apart from each other through end point detection forseparation of the nitride semiconductor layer and the substrate. Aseparation sensing unit for the end point detection may be furtherprovided. The separation sensing unit may perform the end pointdetection by a method for measuring the distance between the separationmembers or pressure monitoring.

The separation apparatus according to the present disclosure may furtherinclude a conveyance apparatus to transfer the separated nitridesemiconductor layer to other substrate or package the separated nitridesemiconductor layer.

The use of the semiconductor stacking structure according to the presentdisclosure and the method and apparatus for separating a nitridesemiconductor layer using the same contributes to the manufacture ofultraviolet light detectors, elastic surface wave devices, LEDs, LDs,and microwave electronic devices, and can be expanded to modules andsystems using the devices. In addition, nitride semiconductorfree-standing substrates can be manufactured. Details of otherembodiments are included in the detailed description and drawings.

Advantageous Effects

According to the present disclosure, the nitride semiconductor layer isgrown on the inorganic thin film on the cavities. The inorganic thinfilm shares and relieves stress with the nitride semiconductor layergrown thereon, and thus, according to the present disclosure, thenitride semiconductor layer is grown with a low defect density and ahigh quality. Therefore, a low defect density and high quality nitridesemiconductor layer is formed, and the reduced crystal defect density innitride semiconductor increases the internal quantum efficiency.

Even though stress occurs in the nitride semiconductor layer due to adifference in thermal expansion coefficient between the substrate andthe nitride semiconductor layer, stress is locally relieved, and as aconsequence, a substrate warpage phenomenon will reduce. Although thereis a difference in thermal expansion coefficient between the substrateand the nitride semiconductor layer, the cavities may be compressed orstretched by the nitride semiconductor layer, resulting in reducedstress applied to the nitride semiconductor layer. Accordingly, it ispossible to use a relative thin substrate on a large scale substrate.

Particularly, because the sacrificial layer pattern is formed acontrolled method such as photolithography or nano-imprint, the cavitiesare not formed irregularly or at random and are formed by a controlledmethod, leading to good reproducibility and superior device uniformity.As a result, it is possible to grow a nitride semiconductor epitaxiallayer with outstanding properties, and realize opto-electronic deviceswith high efficiency and high reliability.

Due to the cavities and voids that can be created when forming thenitride semiconductor layer, the substrate and the nitride semiconductorlayer are easy to mechanically separate from each other. The nitridesemiconductor layer and the substrate can be mechanically separated by asmall mechanical force or impact without applying great energy such as alaser. Accordingly, it is easy to separate the nitride semiconductorlayer from the substrate even though laser lift-off is not used, makingit easy to manufacture vertical LEDs or nitride semiconductorfree-standing substrates.

Particularly, because the separation method and apparatus according tothe present disclosure separates the nitride semiconductor layer fromthe substrate by a mechanical force without using a laser, the time andprocess costs are reduced as compared to a method using a laser, andproduction efficiency increases.

The present disclosure proposes a new mechanism for a method andapparatus for separating a nitride semiconductor layer from a substrateby a mechanical separation method. An inorganic thin film definingcavities, namely, an artificial nano-structure that can be easilydestructed, is formed between the substrate and the nitridesemiconductor layer, thereby separating the nitride semiconductor layerfrom the substrate with no need for an expensive laser device without adeterioration phenomenon caused by a laser.

It is possible to grow the nitride semiconductor layer continuously ordiscontinuously by adjusting the inorganic thin film structure definingthe cavities, the two-dimensional array and the nitride semiconductorlayer growth condition, thereby improving the performance of LEDs andreducing production costs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a semiconductor stacking structure and itsformation method according to the present disclosure.

FIG. 2 is a diagram showing a two-dimensional array of a sacrificiallayer pattern in a semiconductor stacking structure and its formationmethod according to the present disclosure.

FIG. 3 shows various cross sections of cavity in a semiconductorstacking structure according to the present disclosure.

FIG. 4 is a diagram showing various sacrificial layer patterns in amethod for forming a semiconductor stacking structure according to thepresent disclosure, and the resulting shape of an upper surface of aninorganic thin film.

FIG. 5 shows that a part of a nitride semiconductor layer is included inan interfacial layer part in a semiconductor stacking structureaccording to the present disclosure.

FIG. 6 is a diagram showing the shape of an upper surface of a nitridesemiconductor layer in a semiconductor stacking structure according tothe present disclosure.

FIG. 7 shows a pair of plate-shaped separation members included in anapparatus for separating a nitride semiconductor layer according to thepresent disclosure.

FIG. 8 shows another example of separation members included in anapparatus for separating a nitride semiconductor layer according to thepresent disclosure.

FIG. 9 is a schematic diagram of an apparatus for separating a nitridesemiconductor layer according to the present disclosure.

FIG. 10 shows separation of a nitride semiconductor layer from asubstrate under compression using an apparatus for separating a nitridesemiconductor layer according to the present disclosure.

FIG. 11 shows separation of a nitride semiconductor layer from asubstrate under tension using an apparatus for separating a nitridesemiconductor layer according to the present disclosure.

FIG. 12 shows separation of a nitride semiconductor layer from asubstrate under shear using an apparatus for separating a nitridesemiconductor layer according to the present disclosure.

FIG. 13 shows separation of a nitride semiconductor layer from asubstrate under torsion using an apparatus for separating a nitridesemiconductor layer according to the present disclosure.

FIGS. 14 and 15 are SEM images showing an experimental example accordingto the present disclosure.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present disclosure will be described in further detailwith reference to the accompanying drawings. The embodiments describedhereinafter may be modified in many different forms, and the scope ofthe present disclosure is not limited to the following embodiments. Theembodiments of the present disclosure are provided to help personshaving ordinary skill in the art understand the present disclosurecompletely and fully. Accordingly, the shape of the elements in thedrawings is exaggerated for clarity, and elements indicated by the samesymbol in the drawings represent the same element.

The inventors have proposed various research results for relievingstress of a nitride semiconductor layer by forming cavities on asubstrate of heterogeneous material, growing a nitride semiconductorlayer, and deforming the cavities. This application is based on theresearch results of a method for manufacturing a LED or a nitridesemiconductor free-standing or nitride semiconductor substrate in whicha nitride semiconductor layer is separated from a substrate in thesemiconductor stacking structure formed by the method proposed by theinventors, and is transferred or moved to a vertical LED or a horizontalLED, or any type of substrate, and a method and apparatus for separatinga nitride semiconductor layer from a substrate to perform such method.

FIG. 1 is a diagram showing a semiconductor stacking structure and itsformation method according to the present disclosure.

Referring to (a) of FIG. 1, first, a sacrificial layer pattern 20 isformed on a substrate 10. The thickness d of the sacrificial layerpattern 20 may be 0.01˜10 μm and the width w of the sacrificial layerpattern 20 may be 0.01˜10 μm. The thickness d and the width w of thesacrificial layer pattern 20 is determined in consideration of cavity toform in the end. Referring to (a) of FIG. 1, the sacrificial layerpattern 20 is formed uniformly in the same pattern over the entiresubstrate 10. However, the sacrificial layer pattern 20 may be formed inother pattern on the substrate 10, in part.

FIG. 2 is a plan view of a two-dimensional array of the sacrificiallayer pattern 20, showing a part of the substrate that forms a chip.

The sacrificial layer pattern 20 formed on the substrate 10 is of lineand space type, and may extend in the direction of y axis or x axis onthe substrate 10, and FIG. 2 shows that the sacrificial layer pattern 20extends in the direction of y axis.

When a 500 nm line and space pattern is assumed, a chip of dimensions 1mm×1 mm accommodates about 1000 sacrificial layer patterns 20. When thesacrificial layer pattern 20 is made to extend in one direction, a LEDformed using the same has the controlled optical properties in any onedirection, for example, making it possible to adjust polarizationorientation.

Particularly, the sacrificial layer pattern 20 is preferably formed in aline type pattern extending in the direction perpendicular to adirection in which a lateral growth rate of a nitride semiconductorlayer that will be subsequently formed is fast. For example, in FIG. 2,a nitride lateral growth rate in x axis direction is fast. In case thesubstrate 10 is sapphire, the direction in which a lateral growth rateof nitride is fast is <1-100>, and thus, the sacrificial layer pattern20 is formed in a line pattern extending along the <11-20> directionperpendicular thereto. This is to grow a nitride semiconductor layerwhile encouraging Epitaxial Lateral Overgrowth (ELO) starting from thesubstrate 10 as maximum as possible.

The sacrificial layer pattern 20 of line type may be formed over theentire substrate 10, but may be also formed of an island type in whichpatterns are spaced apart. The island type will be preferred to beingformed over the entire substrate 10 in the aspect of bowing prevention.As narrower intervals between the sacrificial layer patterns 20, theshorter length for lateral growth, there is no need to arrange line typepatterns perpendicularly to the direction in which lateral growth isfast.

The sacrificial layer pattern 20 may be formed by various methods suchas photolithography, nano-imprint, and inorganic nanoparticleattachment. According to the present disclosure, a method for formingthe sacrificial layer pattern 20 is relatively simply, and as comparedto substrate etching in earlier technology such as patterned sapphiresubstrate (PSS)a, the substrate is less damaged and the process can besimplified.

The substrate 10 where various sacrificial layer patterns 20 are formedas described above includes all monocrystalline substrates ofheterogeneous material used to grow a heterogeneous epitaxial layer of anitride semiconductor layer, such as sapphire, silicon, SiC, and GaAssubstrates, and in this embodiment, a sapphire substrate is preferred.

After the sacrificial layer pattern 20 is formed as shown in (a) of FIG.1, referring to (b) of FIG. 1, an inorganic thin film 30 is formed onthe sacrificial layer pattern 20. The inorganic thin film 30subsequently defines cavities between the inorganic thin film 30 and thesubstrate 10, and preferably, the inorganic thin film 30 is formedwithin the temperature range in which the sacrificial layer pattern 20is not deformed. The inorganic thin film 30 has a sufficient thicknessto stably maintain the original shape of the structure after thesacrificial layer pattern 20 is removed. A process for forming theinorganic thin film 30 uses various methods such as Atomic LayerDeposition (ALD), wet synthesis, metal deposition and oxidation, andsputtering. To form structurally stable cavities on the substrate 10, itis advantageous to bring a part of the inorganic thin film 30 intodirect contact with the substrate 10 when forming the inorganic thinfilm 30. The inorganic thin film 30 may be at least one of oxide ornitride including silica (SiO₂), alumina (Al₂O₃), titania (TiO₂),zirconia (ZrO₂), yttria (Y₂O₃)-zirconia, copper oxide (CuO, Cu₂O),tantalum oxide (Ta₂O₅), aluminum nitride (AlN), and silicon nitride(Si₃N₄), and in this embodiment, alumina is preferred. By adjusting atleast one of the composition, strength and thickness of the inorganicthin film 30, it is possible to regulate stress applied to a nitridesemiconductor layer subsequently formed on the structure using the same.As shown, the inorganic thin film 30 is formed over the entire substrate10, covering the sacrificial layer pattern 20.

In preferred embodiments, alumina may be formed with a uniform thicknessto conform to the shape of the substrate 10 and the sacrificial layerpattern 20 by a deposition method such as ALD. Instead of the depositionmethod, a wet synthesis method using a wet solution can be used. Afterthe wet solution is uniformly coated to conform to the shape of thesubstrate 10 and the sacrificial layer pattern 20, alumina may besynthesized through heating, drying, or a chemical reaction. Forexample, aluminum precursor powder such as aluminum chloride (AlCl₃) ismixed with a solvent such as tetrachloroethylene (C₂Cl₄), and then isapplied to and coated on the substrate 10 with the sacrificial layerpattern 20, followed by heating in an oxygen atmosphere to cause areaction, creating alumina thin film coating. Alternatively, after ametal Al thin film is deposited by a method such as sputtering, anoxidation process may be performed to form alumina. The alumina isformed in an amorphous state or in a polycrystalline state of finegrains.

After the inorganic thin film 30 is formed, the sacrificial layerpattern 20 is selectively removed from the substrate 10 as shown in (c)of FIG. 1. Because the sacrificial layer pattern 20 is polymer such as aphotoresist film, resin for nano-imprint or organic nanoparticles, amethod for easy removal is heating. The photoresist film having theautoignition temperature of approximately 600° C. can be easily removedby heat. Furthermore, for easier removal by burning using an oxidationprocess, a chemical reaction with gas including oxygen may be added. Ifit is heated at high temperature in an oxygen atmosphere, polymercomponents will be easily removed by a thermal decomposition process,commonly called ashing. For example, the sacrificial layer pattern 20 isremoved by thermal treatment in an oxygen atmosphere. In the case thatthermal treatment in oxygen atmosphere is not proper, for example, inthe case that the substrate 100 is a silicon substrate, and there isconcern about oxide generation, wet removal using an organic solvent canbe used. After the sacrificial layer pattern 20 is removed, cavities Cdefined by the substrate 10 and the inorganic thin film 30 may be formedas shown in (c) of FIG. 1. Although a plurality of cavities C separatedfrom each other is formed in this embodiment, the shape of the cavitiesmay change depending on the shape of the sacrificial layer pattern 20formed at the initial time. The cavities have an inverse shape of thesacrificial layer pattern.

The inorganic thin film 30 in an as-deposited state is generallyamorphous or has poly crystals of fine grains. After the cavities C areformed by removing the sacrificial layer pattern 20, it is preferred toperform thermal treatment to densify and crystallize the amorphous orpolycrystalline inorganic thin film 30.

The thermal treatment removing the sacrificial layer pattern 20 and thethermal treatment of the inorganic thin film 30 may be performed withthe gradually increasing temperature or by a continuous process. In thecase that the inorganic thin film 30 is a material of the samecomposition as the substrate 10 like the case that the substrate 10 is asapphire substrate and the inorganic thin film 30 is alumina, if it isheated to, for example, approximately 1000° C., the inorganic thin film30 becomes an inorganic thin film 30′ crystallized with the samecrystalline structure as the substrate 10 by thermal treatment as shownin (d) of FIG. 1. Accordingly, the interface between the crystallizedinorganic thin film 30′ and the substrate 10 (as indicated as a dottedline in the drawing) disappears. The reason is that a direct contactwith the substrate 10 and solid phase epitaxy growth at the inorganicthin film 30 part occurs during high temperature thermal treatment, andcrystallization occurs along the crystal direction of the substrate 10.The solid phase epitaxy starts from the interface between the substrate10 and the inorganic thin film 30, and in the case that the inorganicthin film 30 is amorphous, the finally crystallized inorganic thin film30′ becomes polycrystalline, or the nano polycrystals increases in size,or in the most preferable case, change to a single crystal like thesubstrate 10. The crystallization preferably occurs over at least a partof the inorganic thin film 30, in particular, the entire inorganic thinfilm 30, and the crystallized inorganic thin film 30′ parts on thecavities C acts as a seed in the subsequent growth of a nitridesemiconductor epitaxial layer, so the inorganic thin film 30′ parts onthe cavities C needs to be crystallized.

Subsequently, as shown in (e) of FIG. 1, a nitride semiconductor layer50 is further formed on the crystallized inorganic thin film 30′. Thenitride semiconductor layer 50 may be formed with a multilayer structureincluding an optimum buffer layer. The nitride semiconductor layer 50includes all nitride semiconductor materials such as GaN, InN, AlN ortheir combination Ga_(x)Al_(y)In_(z)N(0<x,y,z<1). The bandgap may beadjusted based on the material type of the nitride semiconductor layer50 to emit light in the ultraviolet, visible and infrared ranges. Inthis instance, for the nitride semiconductor layer 50, the seed does notgrow on the substrate 10, and grows from the crystallized inorganic thinfilm 30′ parts on the cavities C (the left side picture in (e) of FIG.1). The deposition temperature and the pressure and the flow rate of gasmay be adjusted to grow the nitride semiconductor layer 50 from thecrystallized inorganic thin film 30′ on the cavities C.

The parts grown therefrom under the growth condition are combined toform a thin film, and voids V may be formed at the areas between thecavities C (the right side picture in (e) of FIG. 1). According toembodiments, before the nitride semiconductor layer 50 is combined,growth may be terminated. That is, the nitride semiconductor layer 50 isformed as a plurality of nitride semiconductor layers separated fromeach other by adjusting the epitaxial layer growth time. According toembodiments, a void V may not be formed.

Even though the nitride semiconductor layer is combined, if some partsare combined and some parts are not combined by adjusting the distancebetween the cavities C, the nitride semiconductor layer may be formedcontinuously or discontinuously in the horizontal direction. A partincluding the inorganic thin film 30′, the cavities C and the optionalvoids V is referred to as an “interfacial layer” in the specification.By adjusting the configuration of the interfacial layer, the nitridesemiconductor layer 50 may be also formed as a plurality of nitridesemiconductor layers separated from each other.

If the nitride semiconductor layer 50 grows on the substrate 10 betweenthe cavities C, in this instance, a film is formed on the substrate 10by an ELO method, and overgrows in the horizontal direction on thecavities C and will be combined. However, in the present disclosure, thenitride semiconductor layer 50 does not grow on the substrate 10, andgrows from the crystallized inorganic thin film 30′ parts on thecavities C, so the nitride semiconductor layer 50 is formed in acompletely different manner from an ELO method.

As the inorganic thin film 30′ crystallized according to the presentdisclosure shares and relieves stress with the nitride semiconductorlayer 50 grown thereon, the inorganic thin film 30′ serves as acompliant layer and is grown while stress that may generate dislocationis relieved, and thus, low defect density and high quality growth isachieved.

The stress caused by a physical difference between the substrate and thethin film is converted to elastic energy at the interface, and becomes adriving force that generates dislocation. In normal case, because thethickness of the substrate is very thicker than the thin film,deformation is difficult, and instead, dislocation is generated in thethin film and stress is relieved. In this instance, when a thin filmlarger than or equal to a predetermined thickness or a criticalthickness is grown, the elastic energy at the interface is greater thanthe generation energy of dislocation, so dislocation starts to generate.However, in the case of the present disclosure, because the criticalthickness is larger when the inorganic thin film 30′ is thinner than thenitride semiconductor layer 50, dislocation generation of the nitridesemiconductor layer 50 is reduced. If the inorganic thin film 30′ isenough thinner than the nitride semiconductor layer 50 as above, it canbe said that the roles of the substrate and the thin film in normal casewere changed, and the nitride semiconductor layer 50 grows in a statethat dislocation occurs less. Accordingly, the nitride semiconductorlayer 50 can be formed with a low defect density and a high quality, andbecause the nitride semiconductor crystal defect density reduces, theinternal quantum efficiency in the manufacture of LEDs can be increased.

The semiconductor stacking structure 100 according to the presentdisclosure formed by the above method includes the monocrystallinesubstrate 10 of a heterogeneous material from nitride semiconductor andthe crystallized inorganic thin film 30′ as shown in the right picturein (e) of FIG. 1. A plurality of cavities C that is separated from eachother between the substrate 10 and the inorganic thin film 30′ isdefined to have controlled shape and size and a two-dimensional array.The semiconductor stacking structure 100 includes the nitridesemiconductor layer 50 that grows on the inorganic thin film 30′crystallized on the cavities C and is combined to form the voids V atthe areas between the cavities C.

The inorganic thin film 30′ includes a leg portion 30 a that comes intocontact with the substrate 10 and an upper surface portion 30 b thatextends from the leg portion 30 a and is parallel to the substrate 10.The cavities C are where the sacrificial layer pattern 20 is removedaway during a formation method. Accordingly, the cavities C conform theshape and size and two-dimensional array of the sacrificial layerpattern 20. Thus, for the cavities C to have the controlled shape andsize and two-dimensional array, the shape and size and two-dimensionalarray of the sacrificial layer pattern 20 needs to be set. In thisembodiment, the cavities C are uniformly defined in the same patternover the entire substrate 10 according to the design of the sacrificiallayer pattern 20. However, the cavities may be defined in a locallydifferent pattern according to the design of the sacrificial layerpattern.

Because the cavities C exist, if there is a difference in thermalexpansion coefficient between the substrate 10 and the nitridesemiconductor layer 50 formed thereon, the cavities C are stretched orcompressed in the surface direction, causing a local deformation, sostress energy is consumed. Accordingly, thermal stress applied to thenitride semiconductor layer 50 can be reduced, and thus, a warpagephenomenon of the substrate 10 can be reduced. Accordingly, it ispossible to use the substrate 10 with a relatively thin thickness evenon large scale.

Particularly, because the cavities C can be controlled by adjusting theshape, size, and two-dimensional array of the sacrificial layer pattern,it is possible to adjust the optical properties, for example, emissionpattern of LEDs manufactured from the semiconductor stacking structure100. Furthermore, because the sacrificial layer pattern 20 is formed bythe controlled method such as photolithography or nano-imprint whenforming the sacrificial layer pattern 20, the cavities C are not formedirregularly or at random, and are formed by the controlled method,leading to good reproducibility and superior device uniformity.

As a result, the nitride semiconductor layer 50 having outstandingproperties can be epitaxially grown, and thus, opto-electronic deviceswith high efficiency and high reliability can be realized. Furthermore,with the increasing light extraction efficiency, high output LDs andLEDs can be realized.

The semiconductor stacking structure according to the present disclosureincludes the substrate 10 and the nitride semiconductor layer 50connected with the interfacial layer interposed therebetween. Theinterfacial layer is where the substrate 10 and the nitridesemiconductor layer 50 are mechanically separated at an extent by thecavities C and the optional voids V, and thus is in a state in whichstress occurrence is further suppressed, and after the nitridesemiconductor layer 50 is grown, the nitride semiconductor layer 50 andthe substrate 10 can be separated by the separation method and apparatusaccording to the present disclosure as shown in (f) of FIG. 1.

If a nitride semiconductor layer is grown on a substrate according togeneral conventional technology, the nitride semiconductor layer and thesubstrate are joined on atomic level, and to separate the nitridesemiconductor layer from the substrate, a special process such as laserlift-off is needed. However, in the present disclosure, the inorganicthin film 30′ such as a membrane or a bridge is present in theinterfacial layer, making it easy to separate the nitride semiconductorlayer 50 from the substrate 10 by destructing the inorganic thin film30′ or separating the interface between the inorganic thin film 30′ andthe substrate 10 with a small mechanical force without using laserlift-off. Because separation is achieved with a small mechanical forcesuch as tension or compression, separation is achieved without warpageor cracking or chipping of the nitride semiconductor layer 50.

Accordingly, it is very advantageous in the field of applications whereseparation of the substrate 10 and the nitride semiconductor layer 50 isnecessary, for example, the manufacture of a vertical LED or ahorizontal LED, a LED transferred to a certain substrate, and recyclingof the substrate 10 is easy. In addition, if the nitride semiconductorlayer 50 is formed as a thick film and is separated from the substrate10, it can be used as a nitride semiconductor free-standing substrate,and it makes easy to manufacture a nitride semiconductor substrate as asubstrate of the homogeneous material for good nitride semiconductorgrowth.

The shape of the interfacial layer can be designed variously dependingon the shape of the sacrificial layer pattern 20. In the example shownin FIG. 1, when the sacrificial layer pattern 20 having the crosssection perpendicular to the substrate 10 is rectangular is formed, thecavities C defined by the inorganic thin film 30′ also have arectangular shape in cross section. The cross section of the cavities Cmay have, as shown as various examples in FIG. 3, (a) a square shape, or(b) a trapezoidal shape with the lower surface wider than the uppersurface, or on the contrary, (c) a trapezoidal shape with the lowersurface narrower than the upper surface. In these examples, theinorganic thin film 30′ has a leg portion that comes into contact withthe substrate and an upper surface portion that extends from the legportion and is parallel to the substrate, and the leg portion isperpendicular to the substrate or has a predetermined inclination.However, the upper surface portion is not necessarily parallel to thesubstrate. The upper surface portion may have a curved surface such asconvex or concave, and like the case that the cross section of thecavities is in a triangular shape, the upper surface portion may beabsent. Furthermore, the leg portion does not necessarily have astraight line shape, but the leg portion may also have a curved surfacesuch as convex or concave, and although it is in a straight line shape,the inclination with the substrate may change.

Furthermore, although the sacrificial layer pattern 20 is of a line andspace type in the example shown in FIG. 2, the sacrificial layer patternmay have various shapes as shown as various examples in FIG. 4.

FIG. 4 is a diagram showing various sacrificial layer patterns in themethod for forming a semiconductor stacking structure according to thepresent disclosure, and the resulting shape of the upper surface portionof the inorganic thin film. First, referring to (a), patterns of arectangular shape having the same dimension “a” in width and length areuniformly formed at x and y pitch of “b” when viewed from the top of thesubstrate. In (b), patterns of a square shape having the same dimensionof “a” in width and length are formed at x and y pitch of “b” to createa group G1 and the groups G1 are uniformly formed at x and y pitch of“c”. In (c), patterns of a rectangular shape having different dimensionsof “a” and “a′” in width and length are formed at x pitch of “b′” and ypitch of “d”. b′ and d may be the same or different. In (d), patterns ofa rectangular shape having different dimensions of “a” and “a′” in widthand length are formed at x pitch of “b′” and y pitch of “d” to create agroup G2, and the groups G2 are uniformly formed at x and y pitch of“c′”. b′ and d may be the same or different.

FIG. 5 shows the case in which a part of the nitride semiconductor layeris included in the interfacial layer part in the semiconductor stackingstructure according to the present disclosure. According to theembodiments, at the step (e) described with reference to FIG. 1, thenitride semiconductor layer 50′ may be formed on the inorganic thin film30′ parts between the cavities C during formation of the nitridesemiconductor layer 50. Before the nitride semiconductor layer 50′ growsand goes over the upper surface of the inorganic thin film 30′, when thenitride semiconductor layer 50 grown on the upper surface of theinorganic thin film 30′ is combined, a part of the nitride semiconductorlayer 50′ is filled between the cavities C and voids V are formedbetween the upper portion and the nitride semiconductor layer 50 asshown in FIG. 5.

FIG. 6 is a diagram showing the shape of the upper surface of thenitride semiconductor layer in the semiconductor stacking structureaccording to the present disclosure.

According to the embodiments, before the nitride semiconductor layer 50is combined, growth may be terminated in the step (e) described withreference to FIG. 1. Then, the nitride semiconductor layer 50 is formedas a plurality of nitride semiconductor layers separated from eachother.

(a) of FIG. 6 shows the case in which the sacrificial layer pattern 20as shown in (a) of FIG. 4, for example, is used and growth is terminatedbefore the nitride semiconductor layer 50 is combined. A plurality ofnitride semiconductor layers of a square shape can be obtained. (b) ofFIG. 6 shows the case in which the sacrificial layer pattern 20 as shownin (c) of FIG. 4, for example, is used and growth is terminated beforethe nitride semiconductor layer 50 is combined. A plurality of nitridesemiconductor layers of a rectangular shape can be obtained. Accordingto the desired purpose for which the device is used, for example, in thecase that a LED chip of a rectangular shape such as a LCD BLU (BackLight Unit) is needed, the shape of the cavities C changes depending onthe shape of the sacrificial layer pattern 20 and the shape of theinorganic thin film 30′ thereon that serves as a seed layer changes, sothe shape of the nitride semiconductor layer 50 formed thereon changes.

As described above, the nitride semiconductor layer 50 may be formed asa plurality of nitride semiconductor layers separated from each other,and if the nitride semiconductor layer 50 is formed with a multilayerstructure including an active layer necessary for LED configuration inthe manufacture of the nitride semiconductor layer 50, a plurality ofnitride semiconductor layers 50 separated from each other is alreadymanufactured in the unit of a chip and thus is separated from eachother, so when separating from the substrate 10 by the method forseparating a nitride semiconductor layer according to the presentdisclosure, an advantage is that it is possible to immediately introduceto a packaging process without a conventional device individualizationprocess such as dicing necessary to manufacture a chip unit.

Subsequently, the method and apparatus for separating a nitridesemiconductor layer according to the present disclosure is described inmore detail.

The method for separating a nitride semiconductor layer according to thepresent disclosure includes a first method for separation by applying aforce in vertical direction to the upper surface and the lower surfaceof the semiconductor stacking structure 100 according to the presentdisclosure or a different semiconductor stacking structure having aninterfacial layer with cavities formed between a substrate and a nitridesemiconductor layer as in the present disclosure, a second method forseparation by applying a force in horizontal direction, and a thirdmethod for separation by applying a force in relative circular motion.

The first method includes two conditions, compression and tension.First, the compression condition is a method performed by pressing theupper surface and the lower surface to destruct the inorganic thin filmor the interfacial layer. The tension condition is a method performed bydetaching the upper surface and the lower surface apart from each otherto destruct the inorganic thin film or the interfacial layer. The secondmethod is a method of shear condition performed by destructing theinorganic thin film or the interfacial layer with a shearing forcemoving the upper surface and the lower surface in the horizontaldirection relatively to each other. The third method is a method oftorsion condition performed by twisting the upper surface and the lowersurface around each other into a relatively horizontal circular motionto destruct the inorganic thin film or the interfacial layer.

The first to third methods can be performed in combination. Theseparation by a mechanical force without using a method such as laserradiation is because of the interfacial layer including the cavities Cand the optional voids V in the semiconductor stacking structure 100according to the present disclosure or other semiconductor stackingstructure.

The method for separating a nitride semiconductor layer according to thepresent disclosure is suitable for implementing this separation method.

Although a description is hereinafter provided based on the case ofseparating the nitride semiconductor layer 50 from the substrate 10using the semiconductor stacking structure 100 according to the presentdisclosure, if even a different structure from the semiconductorstacking structure 100 is a semiconductor stacking structure includingan interfacial layer with cavities between a substrate and a nitridesemiconductor layer, it is possible to mechanically separate using theseparation method and apparatus according to the present disclosure.

As shown in FIG. 7, the separation apparatus according to the presentdisclosure includes a pair of plate-shaped separation members 210, 220as jigs respectively applied to the upper surface and the lower surfaceof the semiconductor stacking structure 100.

The first separation member 210 is placed on the lower surface of thesemiconductor stacking structure, i.e., the substrate 10 side. Thesecond separation member 220 is placed on the upper surface of thesemiconductor stacking structure, i.e., the nitride semiconductor layer50 side. The first separation member 210 and the substrate 10 may betemporarily adhered to each other. Likewise, the second separationmember 220 and the nitride semiconductor layer 50 may be temporarilyadhered to each other. Simple contact without adhesion may be possible.The term temporary as used herein refers to that it exists while theseparation step is being performed, and then is removed later. Thetemporary adhesion may be various methods such as an adhesive layer,adhesive coating, an adhesive tape, an electrostatic force and a forceby vacuum. The pair of separation members 210, 220 may be larger thanthe semiconductor stacking structure 100 to cover the semiconductorstacking structure 100, or may be smaller than the semiconductorstacking structure 100 not to cover the semiconductor stacking structure100.

FIG. 8 shows another example of the separation members 210, 220 includedin the apparatus for separating a nitride semiconductor layer accordingto the present disclosure.

The separation members 210, 220 are generally plate-shaped, but may havemounting grooves S in which the semiconductor stacking structure 100 ismounted. Furthermore, the separation members 210, 220 may further havevacuum supply holes to provide a vacuum force for adsorbing thesemiconductor stacking structure 100 through the mounting grooves S. Thesize of the mounting grooves S may be the same as the size of thesemiconductor stacking structure 100, but may be relatively larger thanthe size of the semiconductor stacking structure 100. In this case, themounting grooves S can mount various semiconductor stacking structuresregardless of the size and shape of the semiconductor stackingstructure. The vacuum supply holes are formed to pass through themounting grooves, and vacuum is provided via the through holes.Accordingly, the mounting grooves S adsorb the semiconductor stackingstructure 100 mounted therein, so that the semiconductor stackingstructure 100 does not move and is stationary. To this end, the vacuumsupply holes are connected to a vacuum supply line connected to a vacuumpump, to supply vacuum from the vacuum pump. Furthermore, the vacuumsupply holes may be formed in various patterns, but to uniformly adsorbthe entire surface of the semiconductor stacking structure 100 or adsorbthe semiconductor stacking structure of various sizes regardless of thesize of the semiconductor stacking structure 100, the vacuum supplyholes may be formed in radial pattern. The mounting grooves S may beformed in only any one of the separation members 210, 220.

The pair of separation members 210, 220 may be introduced to aseparation apparatus 200 including a driving unit 230 which applies anexternal force and a control unit 240 while supporting the semiconductorstacking structure 100 therebetween as shown in FIG. 9. In thisinstance, the separation members 210, 220 may have a temporary adhesivelayer interposed therebetween to support the semiconductor stackingstructure 100 well. Another method is sequential introduction in theorder of introducing the first separation member 210 to the separationapparatus 200 first, placing the semiconductor stacking structure 100thereon, and introducing the second separation member 220. To support orhold the separation members 210, 220 being introduced, the separationapparatus 200 may further include appropriate base member and holdingmember.

Instead, the pair of separation members 210, 220 may be configured aspart of the separation apparatus 200. In this instance, it is ready forseparation step in the manner of placing the semiconductor stackingstructure 100 on the first separation member 210, and moving the secondseparation member 220 to the semiconductor stacking structure 100 sideto allow the separation members 210, 220 to support the semiconductorstacking structure 100, or moving the second separation member 220 apartfrom the semiconductor stacking structure 100 to allow the firstseparation member 210 to support the semiconductor stacking structure100.

To facilitate absorption/desorption in response to current on/off, anelectrostatic force and a force by vacuum may be preferable for theseparation members 210, 220 to support the semiconductor stackingstructure 100, and to this end, the separation apparatus 200 may furtherinclude various components such as an electrostatic generation deviceand a vacuum pump.

For mechanical separation of the substrate 10 and the nitridesemiconductor layer 50, the separation apparatus 200 may apply at leastone of relative compression, tension, shear and torsion or itscombination, to the pair of separation members 210, 220. As theseconditions are created by the relative movement of the separationmembers 210, 220, any of the separation members 210, 220 may bestationary and an external force by the driving unit 230 may be appliedto the other. Preferably, it is preferred that the separation memberplaced on the lower side is stationary in terms of stability. Althoughthis embodiment shows that the separation member placed on the lowerside is the first separation member 210 contacting with the substrate10, the second separation member 220 contacting with the nitridesemiconductor layer 50 may be placed on the lower side.

First, to apply the first method, the driving unit 230 is equipped witha driving means to drive, in the vertical direction, the secondseparation member 220 placed on the upper side among the separationmembers 210, 220 facing each other. The driving means is, for example,an air cylinder, a pneumatic motor, an electric motor or a hydraulicmotor, and drives the second separation member 220 in the verticaldirection (upward and downward) until the substrate 10 and the nitridesemiconductor layer 50 are separated.

In the first method, to create a compression condition, the driving unit230 drives the second separation member 220 downwards to provide acompression force. (a) of FIG. 10 shows the case in which the nitridesemiconductor layer 50 and the substrate 10 are separated undercompression. (b) of FIG. 10 shows the case in which the nitridesemiconductor layer 50 and the substrate 10 are separated by destructingthe inorganic thin film 30′. In this instance, immediately after thenitride semiconductor layer 50 and the substrate 10 are separated by thedestruction of the inorganic thin film 30′, the destruction of thenitride semiconductor layer 50 can be prevented by releasing the forcepressing down the second separation member 220. The destructed part ofthe inorganic thin film 30′ may be adhered to the nitride semiconductorlayer 50.

Accordingly, in the case of compression condition creation, end pointdetection is needed, and in the end point detection, the control unit240 controls the driving unit 230 to stop the movement of the secondseparation member 220 in that state or move up the second separationmember 220. The end point detection can implement the following methodand apparatus.

A separation sensing unit 250 that may be further included in theseparation apparatus 200 may sense the extent to which the nitridesemiconductor layer 50 and the substrate 10 are separated by manymethods. Particularly, the extent to which the nitride semiconductorlayer 50 and the substrate 10 are separated may be sensed by measuringthe distance (can be converted to compressed thickness) between theseparation members 210, 220. The separation sensing unit 250 may beattached at any location where the distance between the separationmembers 210, 220 can be measured. The separation sensing unit 250 is notlimited to a particular type, if it can measure the distance betweenobjects spaced apart from each other in real time, such as a lasersensor, a capacitive sensor, and an encoder.

Provided an initial state in which the semiconductor stacking structure100 is inserted between the separation members 210, 220 is defined as astart point, and if the second separation member 220 moves down to lessthan the thickness of the part where the inorganic thin film 30′ isformed, i.e., the interfacial layer, the time when the lower surface thenitride semiconductor layer 50 and the substrate 10 are determined to beseparated is defined as a separation point, the control unit 240 appliesa predetermined pressure to the second separation member 220 orgradually increases the applied pressure until the separation members210, 220 move to the separation point location, and after the separationpoint location is reached, the operation of the second separation member220 is regulated by controlling the driving unit 230 to completelyrelease the applied pressure or lift up the second separation member220.

As such, using the separation sensing unit 250 and the control unit 240,the applied pressure can be adjusted based on the extent to which thenitride semiconductor layer 50 and the substrate 10 are separated,thereby preventing damage of the nitride semiconductor layer 50 causedby excessive pressure applied in compressed state.

The separation sensing unit 250 may be also implemented by a pressuremonitoring method. This uses the principle that slowly increasingpressure is sensed while the inorganic thin film 30′ endures thecompression force, but rapid pressure changes occur at the moment whenthe inorganic thin film 30′ is destructed by the compression force. Toimplement this method, the separation sensing unit 250 is configured tomonitor the pressure applied to the inorganic thin film 30′. Preferably,in this instance, the separation sensing unit 250 assumes configurationof a load cell. The load cell may be mounted on any of the separationmembers 210, 220, or any of the separation members 210, 220 may berealized as a load cell itself. The load cell is a device for monitoringpressure changes in response to the applied compression force, and themoment at which the pressure is released or rapidly changes through theload cell is determined as a separation point at which the nitridesemiconductor layer 50 and the substrate 10 are separated, and after theseparation point location is reached, the operation of the secondseparation member 220 is regulated by controlling the driving unit 230to completely release the applied pressure or lift up the secondseparation member 220.

Subsequently, to create the tension condition in the first method, whilethe semiconductor stacking structure 100 is surely fixed to theseparation members 210, 220, the driving unit 230 drives the secondseparation member 220 upwards to provide a tensile force. (a) of FIG. 11shows the case in which the nitride semiconductor layer 50 and thesubstrate 10 are separated under tension using the apparatus forseparating a nitride semiconductor layer according to the presentdisclosure. The tension condition is a method performed by detaching theseparation members 210, 220 apart from each other to destruct theinorganic thin film 30′. The tensile force may be applied until thenitride semiconductor layer 50 and the substrate 10 are separated, inother words, until the separation members 210, 220 are spaced fartherapart than before the start of separation. In this instance, end pointdetection is not essential. (b) of FIG. 11 shows the case in which thenitride semiconductor layer 50 and the substrate 10 are separated undertension. In this instance, the inorganic thin film 30′ may be partiallyattached to the nitride semiconductor layer 50 or remain on thesubstrate 10.

Next, to implement the second method or the shear condition, the drivingunit 230 provides a shearing force by pushing the second separationmember 220 in the horizontal direction against the first separationmember 210. (a) of FIG. 12 shows the case in which the nitridesemiconductor layer 50 and the substrate 10 are separated under shearusing the apparatus for separating a nitride semiconductor layeraccording to the present disclosure. The shearing force may be applieduntil the nitride semiconductor layer 50 and the substrate 10 areseparated by destructing the inorganic thin film 30′, in other words,until a relative horizontal movement between the separation members 210,220 occurs. Likewise, in this instance, end point detection is notessential. (b) of FIG. 12 shows the case in which the nitridesemiconductor layer 50 and the substrate 10 are separated under shear.In this instance, the inorganic thin film 30′ may be partially attachedto the nitride semiconductor layer 50 or remain on the substrate 10.

Next, to implement the third method or the torsion condition, thedriving unit 230 provides a force of twisting the second separationmember 220 relative to the first separation member 210 or a rotationalforce around the axis perpendicular to the second separation member 220.(a) of FIG. 13 shows the case in which the nitride semiconductor layer50 and the substrate 10 are separated under torsion using the apparatusfor separating a nitride semiconductor layer according to the presentdisclosure. The rotational force may be applied until the nitridesemiconductor layer 50 and the substrate 10 are separated by destructingthe inorganic thin film 30′, in other words, until a relative circularmotion between the separation members 210, 220 can be made. Likewise, inthis instance, end point detection is not essential. (b) of FIG. 13shows the case in which the nitride semiconductor layer 50 and thesubstrate 10 are separated under torsion. In this instance, theinorganic thin film 30′ may be partially attached to the nitridesemiconductor layer 50 or remain on the substrate 10.

The nitride semiconductor layer 50 separated by the separation methodand apparatus 200 may be transferred to other substrate and processedinto a device type after going through a predetermined process forremoving the attached part or pieces of the inorganic thin film 30′, orwithout such process, and as described with reference to FIG. 6, if thenitride semiconductor layer 50 has been already manufactured in chipunit and separated, the nitride semiconductor layer 50 may be directlyintroduced to a packaging process without a process such as dicing. Totransfer the nitride semiconductor layer 50 separated from the substrate10 to other substrate or introduce the nitride semiconductor layer 50 toother process, the separation apparatus 200 may further include anapparatus (not shown) for conveying the separated nitride semiconductorlayer to a next destination, and an apparatus (not shown) for removingthe parts or pieces of the inorganic thin film 30′ attached to thenitride semiconductor layer 50.

In this embodiment, as the nitride semiconductor layer 50 is temporarilyadhered to the second separation member 220 side, after the secondseparation member 220 facing down is revered, the temporary adhesion isreleased, and to convey the nitride semiconductor layer 50 to a nextdestination, the separation apparatus 200 may have an apparatusconfiguration to reverse the second separation member 220. In the casethat the second separation member 220 side to which the nitridesemiconductor layer 50 is temporarily adhered is formed on the lowerside of the separation apparatus 200, this reversing apparatusconfiguration may not be needed.

The substrate 10 remaining after separation may be recycled for growthof other nitride semiconductor layer. The conveyance of thesemiconductor stacking structure 100, and the substrate 10 and thenitride semiconductor layer 50 separated from each other may beperformed by transfer equipment including a transfer arm.

According to the separation method and apparatus, the substrate and thenitride semiconductor layer can be separated by a small mechanical forcewith no need to use high density high output energy such as a laser. Theprocess and apparatus configuration is simple and the process time isshort. This apparatus does not create a vacuum or particular gasatmosphere, eliminating the need for an airtight chamber space, therebyproviding economic efficiency. Because the method and apparatus canseparate the nitride semiconductor layer from the substrate economicallywithout influencing the grown nitride semiconductor layer, utilizationis high in the field of manufacture of LEDs or nitride semiconductorsubstrate transferred to vertical, horizontal, or any other substratethat need to separate a nitride semiconductor layer. If the nitridesemiconductor layer is separated, heat generated during operation of adevice can be easily removed, and in the case in which a substrateexists, an advantage is to let light trapped in the substrate, notescaping, out, and it is worth being used as substrates of a homogeneousmaterial for nitride semiconductor growth.

Hereinafter, the present disclosure is described in more detail bydescribing experimental results according to the present disclosure.

The test process is as follows. As described with reference to FIG. 1,after a line and space type PR pattern was formed on a sapphiresubstrate, an alumina thin film was formed by ALD at 110° C.Subsequently, thermal treatment was performed in air to remove the PRpattern and thereby form cavities and the alumina thin film wascrystallized. (a) of FIG. 14 is an SEM photographic image showing thecavities and the alumina thin film formed on the sapphire substrate bythis method.

Subsequently, a GaN layer was grown on the alumina thin film. Byselectively growing a GaN layer from the alumina thin film on thecavities through adjusting the growth temperature, the gas flow rate,and the pressure, a GaN layer as shown in (b) of FIG. 14 was obtained.As can be seen in (b) of FIG. 14, the GaN layer was selectively grown atthe cavity part, not the substrate part, and parts of the GaN layer andvoids were formed between the cavities as shown in FIG. 5.

Subsequently, the GaN layer and the sapphire substrate were separatedthrough mechanical separation as proposed by the present disclosure. (a)of FIG. 15 is an SEM photographic image of the GaN layer afterseparation and (b) is an SEM photographic image of the substrate. Aspresented in FIG. 15, the GaN layer and the sapphire substrate could besuccessfully separated through mechanical separation.

Although the preferred embodiments of the present disclosure have beenhereinabove illustrated and described, the present disclosure is notlimited to the above-mentioned particular preferred embodiments, and itis obvious to those skilled in the art to make various modifications inembodiment without departing from the nature of the appended claims, andsuch modification fall within the scope of the appended claims.

What is claimed is:
 1. A semiconductor stacking structure, comprising: amonocrystalline substrate of a material that is heterogeneous relativeto a nitride semiconductor; an inorganic thin film formed on thesubstrate to define cavities between the inorganic thin film and thesubstrate, wherein at least a part of the inorganic thin film iscrystalized with the same crystal structure as the substrate; and anitride semiconductor layer grown from the crystalized inorganic thinfilm on the cavities; wherein the nitride semiconductor layer formsvoids at areas between the cavities.
 2. The semiconductor stackingstructure according to claim 1, wherein the inorganic thin filmcomprises: a leg portion contacting with the substrate; and an uppersurface portion extending from the leg portion.
 3. A method forseparating a nitride semiconductor layer, comprising: forming asacrificial layer pattern on a monocrystalline substrate of a materialthat is heterogeneous relative to a nitride semiconductor; forming aninorganic thin film on the sacrificial layer pattern; removing thesacrificial layer pattern from the substrate with the inorganic thinfilm, to form cavities defined by the substrate and the inorganic thinfilm; crystalizing at least a part of the inorganic thin film with thesame crystal structure as the substrate; and growing a nitridesemiconductor layer from the crystalized inorganic thin film on thecavities to form a semiconductor stacking structure, and subsequently,mechanically separating the nitride semiconductor layer from thesubstrate; wherein the nitride semiconductor layer forms voids at areasbetween the cavities.
 4. A method for separating a nitride semiconductorlayer, comprising: forming a sacrificial layer pattern on amonocrystalline substrate of a material that is heterogeneous relativeto a nitride semiconductor; forming an inorganic thin film on thesacrificial layer pattern; removing the sacrificial layer pattern fromthe substrate with the inorganic thin film, to form cavities defined bythe substrate and the inorganic thin film; crystalizing at least a partof the inorganic thin film with the same crystal structure as thesubstrate; and growing a nitride semiconductor layer from thecrystalized inorganic thin film on the cavities to form a semiconductorstacking structure, and subsequently, mechanically separating thenitride semiconductor layer from the substrate; wherein the mechanicallyseparating is performed by one or any combination of applying a force ina vertical direction to the substrate and the nitride semiconductorlayer relative to each other, applying a force in a horizontal directionto the substrate and the nitride semiconductor layer relative to eachother, and applying a torsional force to the substrate and the nitridesemiconductor layer relative to each other.
 5. The method for separatinga nitride semiconductor layer according to claim 4, wherein end pointdetection is performed by sensing thickness or pressure at which thesubstrate and the nitride semiconductor layer are compressed in verticaldirection.
 6. The method for separating a nitride semiconductor layeraccording to claim 4, after separating the nitride semiconductor layerfrom the substrate, further comprising: transferring the separatednitride semiconductor layer to another substrate or packaging theseparated nitride semiconductor layer.
 7. An apparatus for separating anitride semiconductor layer, wherein the apparatus performs mechanicalseparation of the nitride semiconductor layer from the substrate in thesemiconductor stacking structure defined in claim
 1. 8. The apparatusfor separating a nitride semiconductor layer according to claim 7,wherein the apparatus comprises a pair of separation member as jigsapplied respectively to the substrate and the nitride semiconductorlayer of the semiconductor stacking structure.
 9. The apparatus forseparating a nitride semiconductor layer according to claim 8, whereinthe separation members and the semiconductor stacking structure aretemporarily adhered to each other.
 10. The apparatus for separating anitride semiconductor layer according to claim 9, wherein the temporaryadhesion is any of an adhesive layer, adhesive coating, an adhesivetape, an electrostatic force or a force by vacuum.
 11. The apparatus forseparating a nitride semiconductor layer according to claim 8, whereinat least one of the separation members has a mounting groove, andfurther has a vacuum supply hole to provide a vacuum force for adsorbingthe semiconductor stacking structure through the mounting groove. 12.The apparatus for separating a nitride semiconductor layer according toclaim 7, wherein the apparatus comprises: a driving unit configured toapply an external force to the semiconductor stacking structure; and acontrol unit configured to control the driving unit.
 13. The apparatusfor separating a nitride semiconductor layer according to claim 12,wherein the driving unit applies relative compression, tension, shear,torsion, and its combined external force to the substrate and thenitride semiconductor layer.
 14. The apparatus for separating a nitridesemiconductor layer according to claim 13, wherein the external force isapplied while at least one of a pair of separation members istemporarily adhered to the semiconductor stacking structure, the pair ofseparation members being jigs applied respectively to the substrate andthe nitride semiconductor layer of the semiconductor stacking structure.15. The apparatus for separating a nitride semiconductor layer accordingto claim 14, wherein any of the separation members is fixed, and theexternal force in vertical direction, horizontal direction or rotationis applied to the other separation member against the remaining one. 16.The apparatus for separating a nitride semiconductor layer according toclaim 14, wherein any of the separation members is fixed and the otheris driven in vertical direction against the remaining one to provide acompressive force, and the compressive force is released immediatelyafter the nitride semiconductor layer and the substrate are separated bydestruction of the inorganic thin film or the interfacial layer.
 17. Theapparatus for separating a nitride semiconductor layer according toclaim 16, wherein the control unit controls the driving unit to stoprelative movements of the separation members or move the separationmembers apart from each other through end point detection for separationof the nitride semiconductor layer and the substrate.
 18. The apparatusfor separating a nitride semiconductor layer according to claim 17,wherein the apparatus further comprises a separation sensing unit forthe end point detection.
 19. The apparatus for separating a nitridesemiconductor layer according to claim 18, wherein the separationsensing unit performs the end point detection by a method for measuringa distance between the separation members or pressure monitoring. 20.The apparatus for separating a nitride semiconductor layer according toclaim 7, wherein the apparatus further comprises a conveyance apparatusto transfer the separated nitride semiconductor layer to anothersubstrate or to package the separated nitride semiconductor layer.
 21. Asemiconductor stacking structure, comprising: a monocrystallinesubstrate of a material that is heterogeneous relative to a nitridesemiconductor; an inorganic thin film formed on the substrate to definecavities between the inorganic thin film and the substrate, wherein atleast a part of the inorganic thin film is crystalized with the samecrystal structure as the substrate; and a plurality of nitridesemiconductor layers, each one of the plurality of nitride semiconductorlayers being grown from the crystalized inorganic thin film on one ofthe cavities, respectively, and remaining separated from the other onesof the plurality of nitride semiconductor layers.
 22. The semiconductorstacking structure according to claim 21, wherein each one of theplurality of nitride semiconductor layers extends longitudinally in afirst direction, and is separated from at least some other ones of theplurality of nitride semiconductor layers in a second direction that isorthogonal to the first direction.
 23. The semiconductor stackingstructure according to claim 21, wherein each of the nitridesemiconductor layers is formed with a multilayer structure that includesan active layer capable of emitting light as a part of a light emittingdiode.
 24. A method for separating a nitride semiconductor layer,comprising: forming a sacrificial layer pattern on a monocrystallinesubstrate of a material that is heterogeneous relative to a nitridesemiconductor; forming an inorganic thin film on the sacrificial layerpattern; removing the sacrificial layer pattern from the substrate withthe inorganic thin film, to form cavities defined by the substrate andthe inorganic thin film; crystalizing at least a part of the inorganicthin film with the same crystal structure as the substrate; growing aplurality of nitride semiconductor layers to form a semiconductorstacking structure, each one of the plurality of nitride semiconductorlayers being grown from the crystalized inorganic thin film on one ofthe cavities, respectively, and remaining separated from the other onesof the plurality of nitride semiconductor layers; and after the growingstep, mechanically separating the nitride semiconductor layers from thesubstrate.
 25. The method for separating a nitride semiconductor layeraccording to claim 24, wherein, after the growing step and before themechanically separating step, each one of the plurality of nitridesemiconductor layers extends longitudinally in a first direction, and isseparated from at least some other ones of the plurality of nitridesemiconductor layers in a second direction that is orthogonal to thefirst direction.
 26. The method for separating a nitride semiconductorlayer according to claim 4, wherein the nitride semiconductor layer isformed with a multilayer structure that includes an active layer capableof emitting light as a part of a light emitting diode.
 27. The methodfor separating a nitride semiconductor layer according to claim 4,wherein the nitride semiconductor layer comprises a plurality of nitridesemiconductor layers, each one of the plurality of nitride semiconductorlayers being separated from the other ones of the plurality of nitridesemiconductor layers.
 28. The method for separating a nitridesemiconductor layer according to claim 27, wherein each of the nitridesemiconductor layers is formed with a multilayer structure that includesan active layer capable of emitting light as a part of a light emittingdiode; and wherein, after the mechanically separating step, the methodfurther comprises packaging each of the plurality of nitridesemiconductor layers as a unit of a light emitting diode chip.